Novel co-operation between eotaxin and substance-P in inducing eosinophil-derived neurotoxin release

Eosinophils, chemokines, and neuropeptides are thought to play effector roles in the pathogenesis of allergic diseases such as rhinitis. Eotaxin is a novel C-C chemokine with a potent and relatively specific eosinophil chemoattractant activity that binds selectively to CCR3 receptor, however, its activity in inducing eosinophil granules proteins release is poorly characterized. This study was performed to determine whether eotaxin primes eosinophil exocytosis and whether this co-operates with the sensory neuroimmune-axis. In the present communication, we show that 10 ng/ml eotaxin primed normal human eosinophil for exaggerated eosonophil-derived neurotoxin (EDN) release stimulated by 10(-8) M Substance-P (SP). This novel priming was blocked by; 7B11 and Herbimycin A (HA), the CCR3 antagonist and the tyrosine kinase inhibitor, respectively. SDS-Page studies showed significant tyrosine phosphorylation of several protein residues induced by 10(-8) M SP only after priming with 10 ng/ml eotaxin. These results demonstrate a novel co-operation between eotaxin and SP in inducing eosinophil cytotoxicity, which at least in part involves tyrosine kinases pathway(s).     

Indomethacin alters the effects of substance-P and VIP on isolated airway smooth muscle

Both substance-P and vasoactive intestinal peptide (VIP) have previously been demonstrated to contract and relax, respectively, the isolated guinea pig trachea. In addition, substance-P and VIP have been localized within the pulmonary innervation of various species. In the present studies, substance-P was found to cause a concentration-related contraction of isolated lung parenchymal strips of the guinea pig, as well as isolated tracheal strips. VIP caused a significant concentration-related relaxation of the isolated tracheal strip, but not the lung parenchymal strip. Indomethacin, a prostaglandin synthetase inhibitor, potentiated the contractile response of the trachea to substance-P and inhibited the VIP- and isoproterenol-induced relaxation. These studies are potentially important in understanding the pathogenesis of bronchospastic disorders, since alterations in prostaglandin biosynthesis may result in hyperreactivity of airways to contractile agonists such as neurotransmitters, as well as an inhibition of relaxation induced by endogenous substances such as VIP or β agonists.     

Distribution of bombesin, somatostatin, substance-P and vasoactive intestinal polypeptide in feline and porcine skin

The content and distribution of several regulatory peptides in the skin of cats and pigs, freshly obtained at surgery, have been investigated. Immunoreactive bombesin was evenly distributed at low concentrations in both species, being below the detection limit in the body and nose of the cat, and showing a peak value of 1.6 +/- 0.7 pmol/g in the tip of the pig's ear. Similar concentrations of somatostatin-immunoreactivity (-IR) were found but greater regional variation occurred in the pig with a low in the mid back of 0.4 +/- 0.1 and the highest value in the snout of 3.1 +/- 0.8. Substance-P-IR in the pig showed a marked variation in concentration, apparently parallelling skin sensitivity, with a low in the back of 0.4 +/- 0.7 and higher values around the anus (8.1 +/- 1.6), legs (6.8 +/- 1.8) and snout (13.5 +/- 3.6) whilst in the cat values ranged from 0.3 +/- 0.06 in the body to 5.0 +/- 0.9 in the front footpads. In contrast, vasoactive intestinal polypeptide (VIP)-IR showed greater variability in the cat, being below the assay's detection in the body and highest in the front and rear footpads (17 +/- 7 and 29 +/- 6 respectively), but in the pig most regions exhibited low concentrations with the exception of the snout which peaked at 12.0 +/- 5.0. Immunocytochemical localisation showed the peptides to be present in nerve fibres. Substance-P-IR was particularly localised in the snout of the pig just below the epithelium while VIP-IR was more concentrated in deeper layers, often associated with sweat glands and blood vessels.     

Immunohistochemical localization of glucagon, substance-P and vasoactive intestinal peptide in gastrointestinal tract mucosa of zander

The distribution of specific immunoreactivities in the digestive tract of zander Stizostedion lucioperca , using antisera against substance P (sub P), glucagon and vasocative intestinal peptide (VIP), indicated immunoreactivities against all antisera in the glandular cells. The immunoreactivity was less by comparison in the cells of the lamina epithelialis. The most dense regions of immunoreactive cells were the fundus and pylorus of the stomach, the anterior intestine and the pyloric caeca. Immunoreactivity was determined in the nerves belonging to the myenteric plexus and muscle tissue.     

Two modes of regulation of the phospholipase C-linked substance-P receptor in rat parotid acinar cells.

In rat parotid acinar cells prelabelled with [3H]inositol, substance P (100 nM) induced the formation of [3H]inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. Ins(1,4,5)P3 reached a maximum 7 s after substance P stimulation, and thereafter decreased and reached a stable value at 60 s. When the cells were exposed to substance P for 10, 30, 60, or 300 s, washed, and re-exposed to this peptide, the formation of [3H]inositol trisphosphate (InsP3) was attenuated in a time-dependent manner. In the cells pretreated as described above, the number of [3H]substance-P-binding sites (Bmax) was also decreased. Possible role(s) of Ca2+ and protein kinase (protein kinase C) control mechanisms in regulating substance P responses were investigated. Desensitization of substance P-induced InsP3 was not affected by the Ca2+ ionophore ionomycin, nor was it dependent on Ca2+ mobilization. On the other hand, in the presence of 4 beta-phorbol 12,13-dibutyrate (PDBu) and 12-O-tetradecanoyl-4 beta-phorbol 13-acetate, known activators of protein kinase C, substance P-induced InsP3 formation was inhibited. However, PDBu had no effect on [3H]substance P binding, whether present during the assay or when cells were pretreated. The persistent desensitization of InsP3 formation induced by substance P was not affected by PDBu. These results suggest that the persistent desensitization of InsP3 formation induced by substance P is a homologous process involving down-regulation of the substance P receptor; the mechanism does not appear to involve, or to be affected by, the Ca2+ or protein kinase C signalling systems. Protein kinase C activation can, however, inhibit substance P-induced InsP3 formation, which may indicate the presence of a negative-feedback control on the substance P pathway.     

Localization of NK1 receptors and roles of substance-P in subepithelial fibroblasts of rat intestinal villi

Subepithelial fibroblasts of the intestinal villi, which form a contractile cellular network beneath the epithelium, are in close contact with epithelial cells, nerve varicosities, capillaries, smooth muscles and immune cells, and secrete extracellular matrix molecules, growth factors and cytokines, etc. Cultured subepithelial fibroblasts of the rat duodenal villi display various receptors such as endothelins, ATP, substance-P and bradykinin, and release ATP in response to mechanical stimulation. In this study, the presence of functional NK1 receptors (NK1R) was pharmacologically confirmed in primary culture by Ca(2+) measurement, and the effects of substance-P were measured in an acute preparation of epithelium-free duodenal villi from 2- to 3-week-old rats using a two-photon laser microscope. Substance-P elicited an increase in the intracellular Ca(2+) concentration and contraction of the subepithelial fibroblasts in culture and the isolated villi. The localization of NK1R and substance-P in the villi was examined by light and electron microscopic immunohistochemistry. NK1R-like immunoreactivity was intensely localized on the plasma membrane of villous subepithelial fibroblasts in 10-day- to 4-week-old rats and mice and was decreased or absent in adulthood. The pericryptal fibroblasts of the small and large intestine were NK1R immuno-negative. These villous subepithelial fibroblasts form synapse-like structures with both substance-P-immunopositive and -immunonegative nerve varicosities. Here, we propose that the mutual interaction between villous subepithelial fibroblasts and afferent neurons via substance-P and ATP plays important roles in the maturation of the structure and function of the small intestine.